1. Field of the Invention
This invention relates generally to an apparatus for forming bags, and more particularly, to a tubing machine with a rotating former section for quick changeover from flat tube to gusset tube formers, and vice versa.
2. Description of the Prior Art
Machines for making bags, especially from paper, include tubing machines which form a tube from flat sheets of paper supplied to a tube-forming section. The tube is then separated into discrete open-ended tubes of predetermined length, which are subsequently provided with a bottom and/or top, and possibly other structure, such as a handle, for example, to form a bag.
The tube-forming section of a conventional tubing machine typically forms either a flat tube or a gusset tube. In a flat tube, the opposite edges of the sheets of paper supplied to the tube former are folded inwardly into overlapping relationship with one another to form a flattened tube for subsequent processing. In a gusset tube, the opposite edges of the sheets of paper are also folded inwardly into overlapping relationship with one another, but the opposite sides of the tube thus formed are indented or gusseted to form gusseted sides on the tube.
Conventional tube forming machines include one or more rolls of paper, depending upon how many plies are desired in the bag, arranged to supply continuous flat sheets of paper through apparatus which aligns the edges of the sheets as desired, perforates the sheets and applies adhesive in predetermined patterns to form a lamination consisting of multiple plies of paper, which is then pulled through a tube-forming section that folds the sheets of paper into a tubular configuration. The thus-formed tube is then passed through a breakerhead machine which separates the tubular structure into a plurality of discrete tubes of predetermined length, which are then conveyed through a counter/stacker unit for counting and stacking the discrete tubular sections into bundles for subsequent handling, e.g., applying one or more bag ends and/or handles or other features to the bag.
Conventional apparatus may also include a printing section for applying graphics to an outer ply, and/or one or more of the plies may comprise a plastic or other material to achieve a desired property in the completed bag. The tube-forming section of a conventional machine includes a flat, horizontal former bed positioned to receive the laminated plies of paper as they move from a pasting unit and registration device. The tube-forming section folds the paper into a tube configuration before passing it to the breakerhead unit, which separates the tube into a plurality of discrete tubes of predetermined length. Suitable rollers and paper guides (tube formers) are mounted to the former bed for contacting the paper passing over the former bed to fold it into either a flat tube or a gusseted tube. If a flat tube is being formed, formers of a first type are mounted to the bed, and if a gusseted tube is being formed, formers of a different type are mounted to the former bed. The tube forming section in a conventional tubing machine is thus capable of forming only one type of bag, e.g., flat or gusseted. In order to change from making one type of tube to another, it is necessary to replace the formers on the former bed. This takes considerable time, thereby reducing the production capacity of the machine. Moreover, considerable labor and effort are required in order to make the change-over.
Accordingly, there is need for a tube-forming machine which has a tube-forming section that enables quick change-over from making one type of bag to another type of bag, e.g., from making flat tubes to making gusseted tubes.